Statistical analysis of the reasons for the varying magnetization of the granitoids of the Verkhoyansk-Chukotka fold region and the Okhotsk-Chukotka volcanic belt

The granitoid intrusions are classified into nonmagnetic, weakly magnetic, and strongly Magnetic groups. Various characteristics of the intrusions are examined and an attempt is made to statistically relate these characteristics of the intrusions to the intensity of magnetization. The conclusionsreached are: 1) the intensity of magnetization is closely related to the tectonic environment of emplacement. Intrusions emplaced into residual massifs and fold belts where fracturing is common tend to be magnetic. Those emplaced in regions of prolonged subsidence where fracturing is not common tend to be nonmagnetic. 2) Petrography of the intrusion does not seem to affect magnetization; nor does thetype of country rock. 3) The most highly magnetic intrusions are those emplaced at a depth of about 1 km. The intensity of magnetization drops off sharply for those emplaced at depths less than 1 km; a more gradient drop off is noticed for those emplaced at depths greater than 1 km. 4) The intensity of magnetization is dependent upon the magnetic content in the intrusion. However, totaLiron oxide content is about the same in highly magnetic and nonmagnetic intrusions. 5) Tin deposits seem to be associated with nonmagnetic intrusions and gold deposits with magnetic intrusions. — J. R. Hayes.